An electronic system such as a computer system may take advantage of multiple power supplies which share the load supplying power to the computer system. In a system which uses such paralleled power supplies, it is important to coordinate turn on of all the power supplies when starting up the system. For example, if one power supply turns on before the others, that power supply may detect an overload and shut down before the other power supplies turn on to assist with the load, which can result in system failure. Additionally, coordinating turn on of the power supplies allows the system voltages to ramp to required values monotonically, which is required by some electronic loads.
A typical solution to this problem is the use of an interconnecting signal between the power supplies which does not allow any of the power supplies to turn on until all have indicated readiness to turn on. This solution has disadvantages, however. For example, a single bad power supply will keep the entire computer system from powering on. This result is not always warranted, such as with an n+1 system where an additional power supply is already provided to ensure fault tolerance. Shutting down an n+1 system due to a single bad power supply would defeat the advantage of fault tolerance. Further, providing a separate signal between power supplies is expensive. Thus, a different means of coordinating turn on of paralleled power supplies is desirable.